Process of treating copper ores.



.iconditions' mean,

. processes extract 1,o21 ,ves.

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Speeiflcation of Letters Patent.

anrzona Patented Anne, 1912.

To all whom it may concern:

Be it knownthat LRUnoLr GAHL, 'a subject of the Emperor of Germany;residing at Morenci, inthe-county of Greenlee and State of Arizona,haveinvented certain new and useful Improvements in Processes of TreatingCopper Ores, of which the following is a specification.

This invention'consists in a 'method of treating ores K containingcopper and. is suitable for all classes of ore on which concentrating'processes have any effect. Concen trating processes in this senseembrace .all the processes separating the ore into an en-' riched and animpoveri hed'fraction,whether the acting force be gravityas in ordinarywater and dry concentratiomsurface tension as inconcentration'by'flotation, or oia magnetic or electrical nature as inelectromag. netic and electrostatic processes, or of a different nature.

The object of the invention is to provide a method which will supplementthe wasteful method of concentrating-ores which is in general use atthe, present time. The shortcomings of this method have been realizedheretofore and many attempts have been made to discard it and substitutea leaching process, but such attempts have met with very scant success:As almostall of the copper produced at the present time is derived fromlow-grade sulfid ores, it is evi dent that such a rocess, in order to becommercially-valuable, must be very cheap in operation. For'this reasonall the procof the ore can only esses requiring roastin application.Other have a limited field o the copper ing. Sulfuric acid which hasbeen the principal chemical tried will effect only a very limited savingon most ores. Ferric sulfate which has also been used with'ier withoutsulfuric acid will eifect a goodiextraction when the solution is.sufficiently strong, the temperature sufficiently high and the time ofleaching-sufficiently long. 1 oft ese explains why leaching processesthese chemicalshave not'been successful anjf centration has been usedwhy thewasteful process of mechanical conalmost universally up totheresent time. a

l ha i vered, ne tha a ery igh amis of the copper at a very the processof concentration,

-ing far enough as, while it ,have found that cold without roastk besecured cheaply.-

however, high expenses.

"leachin purpos s Application filed January 28, 1911. serial No.605,297.

can be obtained by combiningthe process of concentration with a leachingprocess employing the two chemicals named above. I

eifect the combination of the two processes first and leaching thetaihngs or impoverished fraction resultby concentrating the ore ing fromthe concentration.

In carrying out my inventionl l m di y 1 whereexisting conditions permitof a change.. While here tofore in standardfp'ractice elaborate systems;

of grinding and regrinding preparatory to 11-;

the actual concentration havebeen used: in orderto prevent suchslimingof the -eco"-fnomic' minerals as would make them unfit formechanical, electrical, magnetic, etc., treatment, my aim ismerelyclosed in particles of gan-guea to prevent sliming of the economicminerals,

makes the centration, it is the best possible preparation for leaching.By

'While it is necessary. to, employ mineral unfit; for con-jto carrygrindto insure practically complete liberation. of the mineral particlesin- 1 do -not try v 7 thus simplifying thegcon;

centrating process I cheapen itw strong leaching solutlonsand to letthem act for a long time, if the attempt is made to subjected to theprocess of concentratioml the copper in a very' short time from theunroasted concentrator tailings, grinding the concentrating plant iseificient. gsuch dilute leaching solutions can be d yery cheaplyfromthe-products of mine, concen- -Ores.or mine water high trator orsmelter.

dilute solutionae ctract extract the copper from theorebefore it isowhenes hex vhas been carried far enough. and

in iron often abound in copper mines or can a high percentage of iron.

The concentrates produced in the concentrating plant often carryThesmelterscan and sulfurous' and. sulfuricytcidjjg in"1their.-,;.

waste gases while scrap-ironrfiaproduced -i1I:'-- every metallurgicalplant- -Whei'e-.-;- the2:1'ron. inthese materlals, is alreadyqilr' ttlierric condi ion e in some mine'waters and lutions prepared from oresits solutions can in certain cases it may b 5 late mix the r n and oredirectl' it. h harge a d le ch the mixture with rso' i zed or mad beused'directlyfor" acid; hus ionis ng ionic en ists Tag WhlCllCiLIl-ibflconverted into ferrous sulfate iron. I may employ several methods forconditions.

during the leaching. But as the solution of iron oxid in this case takesplace very slowly, I prefer first to prepare a solution. of iron oxid insulfuric acid and to apply this solution to the concentrator tailings.

ere local conditions are not favorable to the direct production ofsolutions of in ric sulfate, ferrous sulfate solutions can hequently bemade at low cost.- Thelferruginous-slag of smelter-s, especiallyconverter slag, offers a large supply of ferrous iron by leaching eitherwith sulfurlc acid or with sulfurou's acid in the presence of air.Scrapiron can also be converted into ferrous sul fate by treatingit"with sulfuric acid, or sulfurousjacid in the presence of air, ormaybe used for the. precipitation of copper from solutions, thusproducing ferrous sulfate so- 'lutions.

"Copper solutions for-:the treatment applied occur in copper-mines asmine water and are also produced by this process. Having thus-obtained asolution of ferrous sulfate Iconvert the ferrous iron into ferric ich'one *of them is best this in case depends on local adapted to a certWhere a-site is available fora reservoir of.- large size and where therate of evaporation in the open air ishigh Iconduct the fer: roussolutions 'to this reservoir and allow them to, evaporate. Thesameend'may, of course, also be accomplished by artificial evaporation.Thus I obtain'the dry salt in a more or less oxidized state.. Preferably.I expose this to the combined actioniof heat and air at a temperaturebelow the decomposition point of the basic ferric sulfate formed by thisstep, whichis around 600 C. The ferrous salt may, however, also beheated to a temperature above the I decomposi v tion point of the basicferric sulfate,'whereby ironoxid-- is formedand gases given offconsisting ,mai nly of sulfur trioxid which may be condensed ordissolvedin water and used again for leaching purposes. 'Where local conditionsare unfavorable to the evap-.- oration of 'a large quantity .of water orwhererwater is too valuable to permit of such. procedure, I precipitatethe ferrous ironby lime andoxidize the precipitate, preferably byblowing air through the mix,

ferric hydrate which fiy o e pper.

, different classes,

they may berun to 'ture' -After the oxidationis complete I sgparatewater-and precipitate as far as sirable preferably- 1 decantation anddissolve the ferri ehyclrate in sulfuric acid thus forming ferrics'illfate. I

Of the threebxidationprocesses aboveflde scribe the first yields drybasic ferric'sulmaybe dissolved 5 used as a-*leaching agent. I havefound, I,

fate or at least a substance containing f, a' large proportionof this'compound. This in acid and the solution exceed one per salt acts as adissolvingagent, being reduced by copper minerals although insolublelinwater. The second oxidation process produces ferric oxid which I findadvisable to dissolve in acid, before adding it to the leaching tank.The third process produces --may be dissolved in acid in-the leachingtank itself.

The leaching and the separation of liquid and solids following thelea'chingare car 'ried outby any of the methods known to the any acidthe basic art, as is also the precipitation of the coppei t;

from the resulting solution, ysis, iron, lime or matte. The. inventionas above described may be modified in its application, suchmodifications lying, however, within the-scope of the invention. To someof such possible modifications I desire to callspecialattention: (1.)-Substances of known effect in facilitating e. 9.,- by electrol theextraction of copper minerals, as.for

example salt, chlorin, bleaching powder,

niter, manganese-peroxid or the like may be added to the leachingsolutions, if the increased extraction. warrants this. (2. Shouldiron-ore or roasted concentrates, used as a sourceof iron,

tion, while the iron left in the ore is likewise contain a sufiicicntquanthis may be first extracted available for the preparation of ferricso lution's. (3.) To obtain a thecopper by'combined leaching, it is notnecessary to subject all the tailings from the concentrator 'to theleaching process. By grinding the ore sufiicientlyfine and separatingthe tailings into e. g., into sand and slime high extriiction ofconcentrating and tailings, it is pos'sibleto prepare one classv oftailings containing so little copper, that waste without being subjectedto the leaching process.

It will be understood that the process may be cyclical in character, theferrous solutions remaining after the precipitation of the cop. per,being reoxidized by anyjof the methods described and used for leachingfurther uantities of ore, after such addition of sul- 'ic acid as may berequired. 7

In respect to the specific conditions preferably employed for carryingthe invention into efi'ect, itmay be stated that for leaching lowgradeslime containing for example one percent. of copper, the concentrationof ferri'c. iron in the leaching solution. is usually 'lessthan one percent, while the concentraacid may attain on somewhat tion-ofsulfuric Icent. For leaching higher grade or more granular materials it is adthenextracting the copper from said tail- 10 visable to use strongersolutions. ings by said solution.

I claim: 7

In testimony whereof, I affix my signature The process of treatlngunroasted copper in presence of two Witnesses. t

' ores, which consists in concentrating the ores under conditionsyielding tailingsof such RUDOLF GAHL. de ree of subdivislon that thecopper there- Witnesses:

in 1s substantially soluble in a solution con- FORD F. QUIGLEY,

taining ferric iron and sulfuric acid, and: CHAS. F. SHERMAN.

. Copies of this patent may be obtained for five cents each,byngdressing the Commissioner-.01 Iate'nts,

Washington, D. 0.

